1. Field of the Invention
This invention relates to a musical score display system for automatically displaying a musical score representative of a musical performance effected by an associated musical keyboard instrument such as a piano and an electronic organ.
2. Prior Art
In conventional musical score display systems under consideration, musical notes corresponding to actuated or depressed keys are displayed at equal intervals on an associated display device irrespective of the kind of the musical notes. However, in order to provide a musical score properly representing a musical performance, it is desirable that when two keys A and B are successively actuated or depressed, two musical notes corresponding respectively to the depressed keys A and B should be displayed on the display device at an interval or distance corresponding to a time difference of the actuation of the two keys A and B. In this case, however, the following difficulties are encountered:
(a) Strictly, even when the performer of the musical keyboard thinks that he has depressed two keys A and B simultaneously, there frequently occurs a slight time difference .DELTA.T between the depressions of the two keys A and B. If such time difference is transmitted to the display device, the musical score displayed on the display device does not suitably represent the musical performance intended by the player.
(b) As shown in FIG. 1, key C.sub.3 (a key representative of tone C in the third octave) is depressed at time t.sub.1, and then key C.sub.4 is depressed at time t.sub.2. Then, keys E.sub.4 and D.sub.5 are depressed at time t.sub.3 simultaneously with the release of the depressed keys C.sub.3 and C.sub.4. In this case, a musical note corresponding to key C.sub.3 is first displayed on a display device showing a staff notation. Then, a note corresponding to key C.sub.4 is displayed on the display device and spaced from the note representative of key C.sub.3 by a distance corresponding to a quarter note. Then, notes corresponding respectively to keys E.sub.4 and D.sub.5 are displayed on the display device and spaced from the note representative of key C.sub.4 by a distance corresponding to a quarter note. With this method, however, the time interval between the depressions of keys C.sub.3 and C.sub.4 is not properly displayed in the musical score.
Further, when the distance between the adjacent notes displayed on the display device is determined only by the duration of such notes, the following difficulties arise when a plurality of tones are simultaneously produced by the keyboard, for example, to produce a polyphony:
As shown in FIG. 2A, a musical performance is effected in such a manner that a tone representative of a quarter note C.sub.4 is generated during the generation of a tone representative of a half note C.sub.3. In this case, in the displayed musical score, the interval or distance L.sub.1 between the notes C.sub.3 and C.sub.4 and the interval L.sub.2 between the notes C.sub.4 and E.sub.4 should correspond to a distance corresponding to a duration of a quarter note. Actually, however, when such intervals are determined by the duration of the notes, the intervals correspond respectively to durations of half and quarter notes, as shown in FIG. 2B, these intervals being designated at L.sub.3 and L.sub.4. Thus, the musical score displayed in the display device does not coincide with the actual musical performance effected by the keyboard.